The following is a statement from John Walke, clean air director at the Natural Resources Defense Council:

“Updating these standards will protect us from the tiniest particles that can cause the biggest health problems. By limiting the smoke, soot, metals and other pollution our lungs and hearts absorb, EPA is protecting all of us from asthma attacks, lung cancer, heart disease and premature deaths.”

“This a tremendous win for our health and the environment that could only be achieved by following the best science and upholding the Clean Air Act.”

Background:

The Clean Air Act requires EPA to review air quality standards every five years and update the standards as needed. In 2006, the agency issued new national limits for fine particle pollution, known as PM2.5, or particulate matter 2.5 micrometers in diameter or less -- smaller than a strand of hair. Smaller particles can cause more health impacts because they are able to penetrate deeply into the lungs and heart. A federal court rejected the Bush administration standards in 2009 for their failure to protect public health. EPA was supposed to issue a new set of standards by October 2011 but failed to meet that deadline. A court order issued earlier this month required the agency to issue its new proposal to update the standards today.

Fine particle pollution, or soot, comes from sources like power plants, oil refineries, and diesel trucks and buses. Today's proposal defines how much of this pollution is unhealthy for humans to breathe and sets clean air standards that will ensure healthy air quality. Separate federal and state pollution control programs then will work to meet these standards once finalized.

EPA is expected to issue final air quality updates by December 14.

The Natural Resources Defense Council (NRDC) is an international nonprofit environmental organization with more than 1.4 million members and online activists. Since 1970, our lawyers, scientists, and other environmental specialists have worked to protect the world's natural resources, public health, and the environment. NRDC has offices in New York City, Washington, D.C., Los Angeles, San Francisco, Chicago, Bozeman, MT, and Beijing. Visit us at www.nrdc.org and follow us on Twitter @NRDC.